Periodic cleaning and sanitizing in dairy, food and beverage industries, in food preparation and service businesses are a necessary practice for product quality and public health. Residuals left on equipment surfaces or contaminants found in the process or service environment can promote growth of microorganisms. Protecting the consumer against potential health hazards associated with pathogens or toxins and maintaining the quality of the product or service requires routine removing of residuals from surfaces and effective sanitation to reduce microbial populations.
Visual inspection of the equipment cannot ensure that surfaces are clean or free of microorganisms. Antimicrobial treatments as well as cleaning treatments are therefore required for all critical surfaces in order to reduce microbial population to safe levels established by public health regulations. This process is generally referred to as sanitizing. The practice of sanitation is particularly of concern in food process facilities wherein the cleaning treatment is followed by an antimicrobial treatment applied upon all critical surfaces and environmental surfaces to reduce the microbial population to safe levels established by ordinance. A sanitized surface is, as defined by the Environmental Protection Agency (EPA), a consequence of a process or program containing both an initial cleaning and a subsequent sanitizing treatment which must be separated by a potable water rinse. A sanitizing treatment applied to a cleaned food contact surface must result in a reduction in population of at least 99.999% (5 log) for specified microorganisms as defined by the “Germicidal and Detergent Sanitizing Action of Disinfectants”, Official Methods of Analysis of the Association of Official Analytical Chemists, paragraph 960.09 and applicable sections, 15th Edition, 1990 (EPA Guideline 91-2).
The antimicrobial efficacy of sanitizing treatments is significantly reduced if the surface is not absolutely free of soil and other contaminants prior to the sanitizing step. The presence of residual food soil and/or mineral deposits inhibit sanitizing treatments by acting as physical barriers which shield microorganisms lying within the organic or inorganic layer from the microbicide. Furthermore, chemical interactions between the microbicide and certain contaminants can disrupt the killing mechanism of the microbicide.
With the advent of automated cleaning-in-place (CIP) and sanitize-in-place (SIP) systems, the need for disassembly has been diminished, and cleaning and sanitizing have become much more effective. However, modern food industries still rely on sanitizers to compensate for design deficiencies or operational limitations in their cleaning programs and the probability of very small residual amounts of organic and inorganic soils and biofilms remaining on food contact surfaces after cleaning. In cooperation with these process changes and higher performance expectations, sanitizer treatments must also comply with the increasing demand for safer, less corrosive, more environmentally friendly compositions.
Therefore, a need exists for improving sanitizing treatments to destroy pathogens and food spoilage microorganisms resistant to conventional treatments within the food gathering, food processing, and food serving industries. Various chemicals exhibiting varying degrees of antimicrobial activity have been used in sanitizing operations. Among these are short-chain monocarboxylic acids having less than 20 carbon atoms, quaternary ammonium compounds and hexachlorophene compounds. These compounds have been admixed with various surfactants and water to yield aqueous sanitizing solutions. Sanitizers containing halogen can be corrosive to metal surfaces of food plants and quaternary ammonium compounds which also have been used, strongly adhere to sanitized surfaces even after copious rinsing and may interfere with desired microbial growth during food processing, e.g. fermentation.
On the other hand, one problem associated with the use of short-chain monocarboxylic acids sanitizers is poor use dilution phase stability, particularly at lower water temperatures of 0 to 10° C. Fatty monocarboxylic acids having alkyl chains containing 5 or more carbon atoms, are typically characterized as water insoluble and can oil out or precipitate from solution as a gelatinous flocculant. Solubility tends to decrease with decreasing water temperature and increasing ionic concentration. Furthermore, the oil or precipitate can affix to the very surfaces which the sanitizing solution is intended to sanitize, such as equipment surfaces, leading to a film formation on these surfaces over time. The fatty acid film deposited and left remaining on the equipment surface tends to have a higher pH than the sanitizing solution from which it came resulting in a significantly lowered biocidal efficacy, and, if mixed with food soil, may result in a film matrix which has the potential of harboring bacteria, an effect opposite to that desired.
Furthermore, antimicrobial solutions containing these antimicrobial agents are undesirable for use in food equipment cleaning applications. Residual amounts of the acidic sanitizing solutions which remain in the equipment after cleaning can impart unpleasant tastes and odors to food. The cleaning compositions are difficult to rinse from the cleaned surfaces. Larger amounts of water are required to completely remove conventional sanitizing solutions.
It has been found that antimicrobial activity of acidic sanitizing solutions as defined above can be increased by acidifying the sanitizer solution to a pH below 5, so that acidic sanitizing solutions of this type are generally used in food, beverage, brewery and other industries as a cleaning-in-place (CIP) and/or sanitize-in-place (SIP) solution for processing equipment. While the acidic sanitizing solutions presently available are effective against gram-negative and gram-positive bacterias such as Escherichia coli and Staphylococcus aureus, they are not as efficacious on any yeast or mold contamination which can also be present. In many applications control of yeast infections requires a separate solution that can be costly and time consuming.
Such antimicrobiological solutions are generally produced by admixture of water and an aqueous concentrate containing antimicrobiological agents, water or other diluents and acids capable of yielding a pH below about 5 upon dilutions. However, it is clear that such antimicrobial compositions must also exhibit homogeneity and solution stability during prolonged storage periods, in particular at low temperatures. In order to achieve this, solubilizers or coupling agents are added to the compositions in order to maintain stability of the solution at high acid concentrations at prolonged low temperatures or during repeated freeze/thaw cycles.
Such solubilizers are generally surfactant hydrotropes capable of solubilizing the antimicrobial agent in the acidic concentrate which maintain it in both the concentrate and the diluted antimicrobial solution suitable for conventional use. For this purpose various anionic, zwitterionic and nonionic surfactants or mixtures thereof have been previously employed in such solutions. However, these solubilizers, when used in antimicrobial compositions, tend to cause undesirable foaming, thus requiring the addition of foam suppressants for the CIP application and SIP application. Additionally, these solubilizers do not provide stability over a wide range of storage temperatures.
Therefore, there is a need for providing a stable antimicrobial composition which can provide an antimicrobial solution which is equally effective on gram-negative and gram-positive microorganisms and on yeast and on mould, and the antimicrobial activity of which is unaffected by water hardness and which also provides a low foaming antimicrobial use solution capable of removing intense flavour for instance of soft drinks and which is less corrosive and more environmentally friendly.
Now it has been surprisingly found that this need can be satisfied by a specific antimicrobial sanitizing and/or cleaning composition capable of being diluted with a major amount of a food grade diluent to form an antimicrobial use solution.